Practical tools for measured work
Room Mode & Standing Wave Calculator
Enumerate axial, tangential and oblique room resonances and inspect close low-frequency clusters.
Red lines are axial modes, blue tangential, and grey oblique. Closely spaced modes can reinforce one another, but room response also depends on boundaries and placement.
How it works
How to use it: enter internal room dimensions and the mode order to enumerate. The chart sorts every axial, tangential and oblique resonance below your chosen frequency ceiling.
Formula. f = c/2 x sqrt((n/L)^2 + (m/W)^2 + (p/H)^2), using 343 m/s for sound speed. One non-zero index is axial, two tangential and three oblique.
Example. A 5.5 m room has its first length axial mode near 343/(2 x 5.5) = 31.2 Hz.
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Room length
- 5.5 m
- Room width
- 4.2 m
- Room height
- 2.7 m
- Mode order
- 4
- Chart maximum
- 200 Hz
Primary result: 1,0,0 axial: 31.2 Hz.
Before using the result
- Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
- Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
- When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.
Limitations
Rectangular rigid-boundary theory predicts modal frequencies, not exact peak/null severity. Openings, wall flex, furnishings, temperature, source/listener placement and damping change measured response. Verify with room measurements before buying treatment.
Frequently asked questions
Are axial modes most important?
They involve one room dimension and are often stronger, but tangential and oblique modes still contribute to the measured response.
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